Independent Acquisition of Carnassial Teeth in Fishes and Mammals

Vertebrates evolved tooth replacement over 400 million years ago. Over 200 million years later, the combination of vertical tooth replacement with thecodont implantation (teeth in bone sockets) has been considered a key morphological innovation in mammal evolution. We discovered that an extinct fish taxon, Serrasalmimus secans, that shows this same innovation in a lineage (Serrasalmimidae) that survived the end Cretaceous mass extinction. Carnassial teeth are known in both mammals and pycnodont fish, but these teeth do not share the same tissues nor developmental processes. Therefore, a serrasalmimid pycnodont fish independently acquired mammal-like tooth replacement and implantation, thus showing that fishes and mammals evolved convergent carnassial dental morphologies at about the same time, around 60 Ma, in separate ecosystems.